The present invention relates to the electrical connection of an integrated circuit (i.e., “die”) with its surrounding leadframe structure and, more particularly, to connections designed to carry currents much higher than that normally associated with conventional bonding wires or groups of bonding wires.
In the packaging of integrated circuits, the “chip” or die is typically attached to the die “paddle” or “pad” portion of a leadframe structure by a die-attach adhesive or material, typically a solder paste created as a mixture of solder particles and a flux-containing gel. The die includes contact pads that are electrically connected to respective leads or contact areas on the leadframe by thin bonding wires using ball bond (i.e., “nail-head”) or wedge bond formations and thermocompressive or thermosonic bonding techniques.
In some applications involving higher than usual currents, a plurality of bonding wires can be used to connect various conductive pads on the die to leads, pads, or contact areas on the leadframe to accommodate the current involved. As the current levels increase, the number of bonding wire connections increases to the point where the use of a sufficient plurality of bonding wires to carry the current load becomes impracticable. Rather than use a multitude of bonding wires in high-current applications, such as those involving power-switching or power-handling transistors, connections can be made from the die to the leadframe via a conductive ribbon or pre-formed shape-sustaining clips using copper or a copper alloy, for example, as the conductive material. In those cases where a pre-formed clip is used, a need arises for maintaining the clip in place during processing.